Abstract
The studies are giving an answer to the question whether noble metals undergo reversible segregation and form nanostructures on TiO2(001). It was found out that Au and Pt nanostructures (AuNSs and PtNSs) can be formed on a single-crystalline rutile TiO2(001) substrate. They were obtained by thermal treatment at 1073 K in ultra-high vacuum of thin Au and Pt films deposited by ion sputtering technique. The properties of nanostructures on TiO2(001) were analysed basing on XPS, STM, SEM and GI-XRD data. It is shown that AuNSs and PtNSs, although prepared in similar manner, exhibited significant differences in concentration, size, distribution and calculated polydispersity index. AuNSs appeared to be hemispherical-like and close to monodisperse with lateral size of 13 ± 4 nm. In contrast, PtNSs revealed the existence of two populations in size i.e. 11 ± 4 nm and 39 ± 11 nm and they possessed nanocrystalline structure with clearly exposed Pt(111) facets. Also, compared to previous findings for lighter metals (Fe, Co and Ni), the experiments showed no reversible segregation of Au and Pt on TiO2(001). Thus, the role of diffusion coefficients and masses of the selected ions was discussed to explain the differences in reversible segregation of various metals on TiO2(001) substrate.
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